Controlling flow in granules heat exchanger



Patented Nov. 3, 1970 3,537,511

INVENIORS Gusruv A. Moog Donald L. Gerrh ATTORNEY 3,031,773 5/l962Dunkle United States Patent [72] Inventors Gustav A. Man 3,068,07612/1962 Sackett 222/58 Crestview Hills, Ky., and 3,319,828 5/1967Maxwell 222/58 v figi g t'g gz z Township Primary Examiner-CharlesSukalo pp No. 797,060 Attorneys-Fredrick H. Braun and John V. Gorman[22] Filed Feb. 6, 1969 [45] Patented Nov. 3, 1970 [73] Assignee TheProctor & Gamble Company Cincinnati, Ohio a corporation of Ohio [54]CONTROLLING FLOW IN GRANULES HEAT EXCHANGER 8 Claims, 1 Drawing Fig.

[52] 0.8. CI 165/32, 165/39, 165/1 17, 34/177, 222/58, 222/146 [51] Int.Cl 605d 23/00 [50] Field oi'Search 165/32, 39, 117, 158; 34/l77;222/58,146

[5 6] References Cited UNITED STATES PATENTS ABSTRACT: A weigh duct ismounted for pivotal movement over the inlet to a tubular heat exchangerdesigned for heating or cooling granular material. Flow of granules fromthe bottom outlet of the heat exchanger is regulated by a meteringdevice mounted in the lowermost portion thereof which can be adjusted tocontrol flow through the heat exchanger. The weight of granules in theweigh duct is continuously sensed by a weigh cell which transmits aproportional signal to a set point controller. The set point controllercontinuously sends a signal for properly positioning a control cylinderwhich is used to vary outflow from the heat exchanger through themetering device. Outflow is adjusted and controlled in order to maintainan optimum choked flow condition within the heat exchanger.

BACKGROUND OF THE INVENTION It has been found that products in granularform such as detergent granules, sugar and the like, can be cooled orheated very effectively by merely passing the granules through a heatexchanger containing a plurality of cooling tubes mounted transverselyacross a heat exchange chamber such that the granules flow over theoutside tube surfaces. The secret of effective heat transfer in thesecircumstances is to maintain the heat exchange chamber completely fullof granules rather than let them fall freely through the chamber. Thisresults in maximum contact of the granules as a function of time withrespect to the heat exchange surfaces. The effect is known in the art asa choked flow" condition.

when cooling large quantities of granules, it is oftentimes verydifficult to maintain a constant choked flow condition. While the priorart was aware of the advantages of choked flow heat exchange forgranular products, there was no suggestion of a device that wouldeffectively maintain this condition for very large volumes of granulesand particularly when the rate of flow was varied considerably withrespect to time. As a consequence, one of the basic drawbacks withpreviously known granular heat exchangers was the lack of an effectivedevice for continuously maintaining the condition known as choked flow.

SUMMARY OF THE INVENTION The nature and substance of the invention willbe most readily appreciated by first giving consideration to a number ofits primary objects.

A major object of the invention is the provision of a device forcontrolling flow in a heat exchanger for granular material in order tomaintain a choked flow condition in the heat exchanger at all times forthe purpose of obtaining the most efficient and effective heat exchangepossible under a given set of conditions.

Another object of the invention is the provision of a system of thischaracter in which the proper level for choked flow may be maintained inthe heat exchanger even with very high rates of granules flowtherethrough. That is, it is an an objective to obtain a device that iseffective with product turnover in the heat exchanger occurring asfrequently as once or twice per minute.

A further object of the invention is the provision of a device havingmeans to accomplish uniform plug flow of granular material throughtubular heat exchangers of large cross section.

These and other objects are obtained by the provision of a weigh ductmounted for pivotal movement above a heat exchanger and located suchthat all of the granular project flows through the weigh duct prior toflowing into the heat exchanger. The weigh duct contains a plurality ofweight support members which are designed to support the weight ofgranular material therein at any given time. The weight of granules inthe weigh duct is detected by an appropriate weight sensing device whichtransmits a signal proportional to the weight sensed to a set pointcontroller. A flow metering device is located at the bottom of the heatexchanger and is capable of constant adjustment in order to controloutflow therefrom. The flow metering device is automatically adjusted inresponse to the signal continuously transmitted by the set pointcontroller in response to the signal it receives from the weigh cellsuch that the heat exchanger is maintained in choked condition under allconditions of flow.

BRIEF DESCRIPTION OF THE DRAWING While the specification concludes withclaims particularly pointing out and distinctly claiming the subjectmatter regarded as forming the present invention, it is believed theinvention will be better understood from the following description takenin connectionwith the accompanying drawing which illustrates a flowcontrol device as applied to a tubular heat exchanger, the drawing beingan exploded view with portions thereof fragmented in order to facilitatethe illustration thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention will now bedescribed as applied to a tubular heat exchanger designed for thecooling of granular products, e.g., detergent granules or the like. Theheat exchanger 10 is composed of a plurality of side walls there being aplurality of tubes 11 running transversely from side-to-side on theinside of the heat exchanger 10. The ends of the tubes 11 are connected,respectively, to a suitable inlet and outlet (not shown) of a liquidcoolant such as water. The coolant is preferably continuously circulatedthrough the tubes 11 in order to obtain the desired degree of heatexchange as the granular product flows downwardly through the heatexchanger 10 from the opening 12. The heat exchanger 10 itself can takeany of various forms as will be appreciated by persons skilled in theart and the tubes 11 can be smooth or finned, the latter being of thetype described in U.S. Pat. No. 3,372,742 issued Mar. 12, 1968 to JamesN. Forner and entitled APPARATUS FOR HEAT EXCHANGE OR GRANULAR SOLIDS.The above cited patent is assigned to and commonly owned by the assigneeof the present application.

The lower portion of the heat exchanger 10 is provided with a meteringplate 13 which contains a plurality of apertures 14, the latter beingrelatively evenly distributed across the surface of the plate 13. Guiderods 15, 16, 17 and 18 are rigidly mounted in proximity to the lowercorners of the heat exchanger 10 and project downwardly as shown on thedrawrespectively, for sliding movement thereon. Thus it will be apparentthat the relative vertical position of the cone shaped members 20 whichcontrols outflow through the apertures 14 will be dependent upon theposition of the grid device 19 with respect to the metering plate 13 asthe grid structure 19 is positioned on the guide rods 15, l6, l7 and 18.As the grid structure 19 is moved upwardly, the cone shaped members 20will enter the respective aperture 14 to restrict outflow and viceversa.

A suitable mechanism is provided for positioning the grid structure 19on the rods 15, 16, 17 and 18. The mechanism comprises an L-shapedrocker arm 26 and a T-shaped rocker arm 27 journaled on the stud shafts28 and 29, respectively. The stud shafts 28 and 29 are each journaled ina conventional bearing (not shown), the latter being supported on thesame stationary support which may also be used for supporting the heatexchanger 10. The link members 30 and 31 are attached for pivotalmovement, respectively, on the pins 32 and 33 projecting laterally fromthe side members 21. The lower ends of each of the link members 30 and31 are journaled on the rocker arms 26 and 27, respectively. The rockerarms 26 and 27 are linked for movement in unison by the extended linkmember 34.

An essentially similar linkage mechanism is provided on the far side ofthe grid structure 19. The L-shaped rocker arm 35, the T-shaped rockerarm 36 and the extended link member 37 are shown in the drawing. It willbe understood that the remainder of the associated linkage mechanism isidentical to the linkages illustrated on the front side in order thatidentical motions will be imparted to both sides of the grid structure19 as will be appreciated by those skilled in the art. A common pivotshaft 38 interconnects the T-shaped rocker arms 27 and 36. The pivotshaft 38 is coaxial with the stud shaft 29 in order that the same motionis imparted to each of the linkage arrangements on opposite sides of thegrid structure 19. An actuating member 39 having a projecting pin 40extending into the opening 41 is provided there being a similarconnection between the member 39 and the T-shaped rocker arm 36.

A positioning cylinder 42 is mounted on a stationary support and has apiston rod 43 connected to the actuating member 39. Thus it willbe-appreciated that vertical movement by the rod 43 will be transmittedto the rocker arms 26, 27 and 35, 36 by means of the aforesaid mechanismin order to cause upward and/or downward movement of the grid structure19. The movement of the grid structure 19 in turn controls outflow fromthe heat exchanger 10.

Movement of the grid structure 19 is controlled by a mechanism now to bedescribed. A weigh duct 44 is mounted for pivotal movement over theopening 12 such that the lower end of the side walls of the weigh duct44 fit freely within the opening 12. This permits free pivotal movementof the weigh duct 44 while suspended within the opening 12. Theclearance between the lower edge of the weigh duct 44 and the opening 12is sufficiently small and the inherent angle of repose ofthe material inthe heat exchanger 10 is sufficiently large that there is no leakage ofmaterial through this clearance space. it is possible, if desired, toprovide a suitable flexible seal (not shown) that will not interferewith pivotal movement of the weigh duct 44.

The weigh duct 44 is supported between the arms 45 and 46 which arejournaled at one end on the pins 47. A cross member 48 interconnects thearms 45 and 46 at their forward ends. Suitable stationary bearings (notshown) are provided for receiving the pins 47 so that pivotal movementof the weigh duct 44 is possible thereon in response to weightvariations within the weigh duct 44. As illustrated, the weigh duct 44is preferably pivoted on a horizontal axis located laterally beyond theside walls of the weigh duct.

A plurality of transverse bars 49 are provided within the weigh duct 44.The bars 49 are substantially evenly distributed and function as weightsupporting members as the level of granular material builds up in theweigh duct 44 after filling the heat exchanger 10. While the weigh duct44 is illustrated with the transverse bars 49 therein, it will beunderstood that the invention can be carried out with equal facility byreplacing the bars 49 with tubes or any other weight supporting memberssuch as discs, cones, spheres, rods, etc. as will be appreciated bythose skilled in the art.

Means are provided for sensing the weight of material supported by thebars 49 in the weigh duct 44 in order to control outflow from the bottomof the heat exchanger 10. The means illustrated comprise a stationaryweigh cell 50 which has a force imparted thereto by the cross member 48in response to the weight supported by the pivoted arms 45 and 46 whichfluctuates with variations in the weight of material supported in theweigh duct 44. The weigh cell 50 functions as a transmitter forconstantly sending a signal proportional to the weight of material itsenses in the duct 44. The weigh cell 50 can be any one of several wellknown devices designed for carrying out this function and it can beeither pnuematically, hydraulically or electronically controlled andoperated. In a preferred form of the invention, the weigh cell 50 ispneumatically actuated and is a model 502A weight transmitter of thetype available from the Kane Air Scale Company of Glassboro, New Jersey.

The signal proportional to the weight supported in the duct 44 istransmitted from the weigh cell 50 to a conventional set pointcontroller 51 which can also be of the pneumatic, hydraulic orelectronic type depending upon the type of operation preferred. The setpoint controller 51 is used to control and vary as necessary the settingof the rod 43 of the positioning cylinder 42. The position of the rod 43will, of course, control outflow from the heat exchanger 10 by means ofthe previously described mechanism. That is, the set point controller 5kautomatically varies the setting of the piston rod 43 in response to thesignal it receives from the weigh cell 50. in this way the controller 51strives to maintain the weight of granular material substantiallyconstant within the weigh duct 44. This, in turn, is necessary in orderto maintain a choked flow condition within the heat exchanger it).

In a preferred installation, the set point controller 51 was a No. 50two mode stack controller supplied by the Moore Products Company ofSpringhouse, Pennsylvania and the positioning cylinder 42 was a seriesB-SOXR actuator of the type manufactured by Conoflow Corporation ofBlackwood, New Jersey. These control devices are merely examples of acombination that has been successfully used, it being understood thatthe invention is not limited to these specific types. As aforesaid,various combinations of pneumatic, hydraulic and/or electronic devicescan be used to practice the invention and sense the weight of granulesin the weigh duct 44 in order to control outflow from the bottom of theheat exchanger 10 and maintain a choked flow condition therein at alltimes.

It will also be appreciated that various other types of flow controldevices can be utilized in the lower portion of the heat exchanger 10,including, but not limiting to feeder valves, feeder belts, variableslots and converging hoppers. In addition, it is also possible to sensethe weight of granules in the duct 44 by various means such as opticalsystems, radiation absorption systems, indicator type systems and thelike in order to feed a proportional signal to the set point controller51.

While particular embodiments of the invention have been illustrated anddescribed, it will be obvious to those skilled in the art that variouschanges and modifications can be made without departing from the spiritand scope of the invention and it is intended that all such changes andmodifications are within the scope of this invention.

We claim:

1. An apparatus for maintaining choked flow in a heat exchanger forgranular material comprising:

a, a weigh duct suspended over and mounted for pivotal movement abovesaid heat exchanger;

b. weight supporting members mounted in said weigh duct for sensing theweight of granular material reposing in said weigh duct;

c. a flow control mechanism for varying the outflow of granular materialfrom said heat exchanger;

d. means for sensing variations in the weight of material reposing insaid weigh duct and transmitting a signal proportional thereto; and

e. means for controlling the outflow through said flow control mechanismin response to the signal from said sensing means 2. An apparatus formaintaining choked flow in a heat exchanger as claimed in claim 1wherein the weight supporting members comprise a plurality of barsmounted transversely with respect to the direction of flow through saidweigh duct.

3. An apparatus for maintaining choked flow in a heat exchanger asclaimed in claim 1 wherein said flow control mechanism comprises ametering plate mounted transversely in the bottom of said heatexchanger, a plurality of orifices in said metering plate, a gridstructure mounted beneath said metering plate, a plurality of coneshaped members on said grid structure, said cone shaped membersprojecting upwardly in alignment with each of said orifices, and meansfor moving said grid structure to vary the effective opening of saidorifices and to coiitrol outflow from said heat exchanger.

4. An apparatus for maintaining choked flow in a heat exchanger asclaimed in claim 1 wherein said weigh duct is pivoted on a horizontalaxis located laterally beyond the side walls of said weigh duct.

5. An apparatus for maintaining choked flow in a heat exchanger asclaimed in claim 2 wherein said flow control mechanism comprises ametering plate mounted transversely in the bottom of said heatexchanger, a plurality of orifices in said metering plate, a gridstructure mounted beneath said metering plate, a plurality of coneshaped members on said grid structure, said cone shaped membersprojecting upwardly in alignment with each of said orifices, and meansfor moving said grid structure to vary the effective opening of saidorifices and to control outflow from said heat exchanger.

6. An apparatus for maintaining choked flow in a heat exchanger asclaimed in claim 2 wherein said weigh duct is pivoted on a horizontalaxis located laterally beyond the side walls of said weigh duct.

7. An apparatus for maintaining choked flow in a heat exchanger asclaimed in claim 3 wherein said weigh duct is pivoted on a horizontalaxis located laterally beyond the side walls of said weigh duct.

8. An apparatus for maintaining choked flow in a heat exchanger asclaimed in claim 1 wherein:

a. said weigh duct is pivoted on a horizontal axis located laterallybeyond the side walls of said weigh duct;

b. said weight supporting members comprise a plurality of bars mountedtransversely with respect to the direction of flow through said weighduct; and

c. said flow control mechanism comprises a metering plate mountedtransversely in the bottom of said heat exchanger, a plurality oforifices in said metering plate, a grid structure mounted beneath saidmetering plate, a plurality of cone shaped members on said gridstructure, said cone shaped members projecting upwardly in alignmentwith each of said orifices, and means for moving said grid structure tovary the effective opening of said orifices and to control outflow frontsaid heat exchanger.

